The invention relates generally to flue heat reclaimers for use with home heaters or the like.
The present day devices in use today for reclaiming heat from the flues of home heaters or the like have several deficiencies. Such heat reclaimers involve an arrangement wherein a pluralty of heat transfer tubes are mounted to extend transversely across the flue duct passage. Because of the comparatively small air-hot surface contact, this arrangement does not provide sufficient heat transfer from the flue gases to the heat reclaimer. Moreover, the transversely extending heat transfer tubes provide an obstruction to the flow of the flue gases through the flue duct and permit soot to build up to restrict this flow when used with wood and oil stoves. Accordingly, the soot must be cleaned periodically in order to prevent the creation of a serious hazardous condition. Also, the soot buildup reduces the heat transfer effectiveness of the device. The use of above-described devices is prohibited in some states because of safety hazzards.
It is the general object of the invention to provide a flue heat reclaimer which overcomes the deficiencies or the present day devices described above. The flue heat reclaimer of the invention provides for a better heat transfer efficiency than the prior devices, and does not obstruct the flow of gases in the flue. In one construction in accordance with the invention the reclaimer is adapted to fit over the exterior of an existing flue duct. Thus, the flue heat reclaimer of the invention does not require cutting into the interior of the flue duct as is the case with the prior art devices. The flue heat reclaimer of the invention can also be pre-assembled and inserted as a section in the flue duct. Moreover, the flue heat reclaimer of the invention is less expensive to make and simpler to install than the prior art devices.
Briefly stated, the flue heat reclaimer of the invention comprises a spiral-shaped divider which fits over the flue duct with its inner edge adjacent thereto, and a cylindrical outer tube adapted to be mounted on the flue duct and having a diameter greater than the diameter of the flue duct, the divider being adapted to fit within the outer tube with its outer edge adjacent thereto. The flue heat reclaimer also is provided with end caps enclosing the ends of the outer tube. The end caps, the outer tube and the divider cooperate with the exterior of the flue duct to define a spiral-shaped heat exchange passage extending around the exterior of the flue duct. Fan means are provided to cause air to flow through the heat exchange passage so that the temperature of this flowing air is raised by reason of its extended heat exchange relationship with the exterior of the flue duct. The heat reclaimer is most desirably provided with a helical-shaped divider and means for restricting the air flow through the heat exchange passage in a manner to create turbulent flow and increase the heat exchange action that occurs.